How many different triangles are there in the figure?

Problems

Grades: 3rd to 5th

Geometry

Classify two-dimensional figures into categories based on their properties.

5.G.B.4

It’s not too hard to form the number 9 using three 3’s and any of the four standard
mathematical operations +, –, × and ÷. But can you come up with four different
solutions, each of which uses only one of the four operations? (Other standard
mathematical symbols can be used as needed.)

**9
= 3 + 3 + 3**

Problems

Grades: 3rd to 5th

Algebraic Thinking

Write and interpret numerical expressions.

Multiply and divide within 100.

3.OA.C.7, 5.OA.A.1

When the ends of the rope at left are pulled in opposite directions, how many knots will be formed along the rope's length?

Problems

Write 2014 with the first four prime numbers, with the
aid of the operations addition, multiplication and exponentiation.

Problems

Grades: 6th to 8th, 3rd to 5th

Expression/Equation

Algebraic Thinking

Apply and extend previous understandings of arithmetic to algebraic expressions.

Gain familiarity with factors and multiples.

Multiply and divide within 100.

3.OA.C.7, 4.OA.B.4, 6.EE.A.1

Equations to solve in your
head:

Is this a joke? Not if you can
multiply the first equation by 6,751 and the second by 3,249 in your head, and
not if you use a second, simpler method.

Problems

Grades: 9th to 12th, 6th to 8th

Algebra

Expression/Equation

Reasoning with Equations and Inequalities

Analyze and solve linear equations and pairs of simultaneous linear equations.

8.EE.C.8b, HSA-REI.C.6, HSA-REI.C.5